Disks on which a signal can be recorded by using a laser beam are now available. A CD-R is known as one of such disks on which a signal can be recorded by using a laser beam. In this case, a CD-R is required to have read-out characteristics which are equivalent to those of a CD. Then, a CD is designed to record a signal by a combination of portions (called “lands”) in which the amount of light of a reflected laser beam is increased when it is irradiated by a laser beam and portions (called “pits”) in which the amount or light of a reflected laser beam is decreased when it is diffracted.
Therefore, the CD-R is provided with, as a recording layer, a dye layer having a high reflectance of a laser beam and which corresponds to the land. When this dye layer is irradiated by a laser beam, the dye layer generates heat from its point at which it is irradiated by a laser beam and thereby this point is deformed. This deformed portion has a reflectance lower than that of the dye layer and becomes a pit. Accordingly, the intensity of a laser beam is modulated by a recording signal, whereby the recording signal can be recorded on the CD-R.
In this case, however, since the dye layer produces intensive heat with the irradiation of the laser beam and thereby the recording signal can be recorded, the laser beam should be focused on the dye layer with high accuracy. Moreover, the position at which the CD-R is irradiated by the laser beam has to be prevented from being displaced from a track. However, when a CD-R or a recording and reproducing optical head (optical pickup) is vibrated, it is unavoidable that the properly-focused state of the laser beam is broken or that the track position (position irradiated by a laser beam) is displaced.
To solve this problem, a recording apparatus in actual practice is provided with a laser beam focusing and tracking servo system. Therefore, when vibrations to the CD-R or to the optical head are not so large, this servo system may respond to such vibrations to thereby control the optical head in such a manner that the optical head can escape from the influence exerted by such vibrations. Thus, a recording signal can be recorded on the disk normally. Further, when vibrations are so large that the optical head becomes unable to continue the recording, the recording made by the optical head is stopped for a moment. At the same time, when the vibrations are removed, if the recording is resumed from where the recording was stopped on the disk, then a recording signal can be recorded on the disk normally.
However, even when vibrations are small enough to cause the servo system to respond to such small vibrations normally, it is unavoidable that a laser beam is not properly focused or that a tracking error occurs due to the reasons which will follow. As a consequence, it is frequently observed that a recording signal cannot be recorded on the CD-R satisfactorily.
That is, the influences exerted upon the recording layer of the CD-R by vibrations generally exist in both of the focusing direction and the tracking direction. However, when the vibrations are displaced in one direction of either the focusing direction or the tracking direction, since the level of an error component (error component produced due to vibrations) contained in a focusing servo signal or a tracking servo signal reaches a certain level, the level of the error component can be detected and the recording can be stopped.
However, even when vibrations are of the same magnitude, if vibration components are dispersed into both of the focusing direction and the tracking direction, then individual vibration components become small with the result that error components (error components produced due to vibrations) contained in the focusing servo signal and the tracking servo signal reach very small values, respectively. In addition, a focusing error signal and a tracking error signal contain error components produced due to an eccentricity or disk skew of the CD-R.
For this reason, when the vibration components are dispersed into the focusing direction and the tracking direction, it is very difficult to detect the error components produced due to the vibrations. Therefore, there is a semblance as if the recording of the recording signal on the disk was ended normally.
As described above, even with such small vibrations, it is unavoidable that there occurs a slight displacement of a focus or a very small tracking error. As a result, the recording signal cannot be recorded on the CD-R satisfactorily.
Therefore, in order to cope with such situations, as is disclosed in a Japanese laid-open patent application No. 2000-90448, for example, it has so far been proposed that a recording apparatus be provided with a vibration detecting sensor capable of detecting the vibrations on the outside of the optical head and the CD-R. According to this method, however, since vibrations at the very portion that is performing a recording can not be necessarily being detected, vibrations which are harmful for the recording cannot always be detected, and a user tends to fail in the recording of the recording signal on the disk accordingly.
Then, in the case of a digital camera using a CD-R as a recording medium, when such digital camera fails to record an image signal, because the digital camera is unable to recapture the image signal to be recorded, there should be no excuse for failing in the recording.
On the other hand, when recording signals to be recorded on the CD-R are those obtained from other suitable media or equipment such as CDs or computers, even if a user fails in the recording, then a signal to be recorded on the disk can be obtained again, and hence a user is able to record the recording signal on the disk once more. However, until all recorded materials are played back thoroughly, a user is unable to determine whether or not the first recording has been made normally. Therefore, checking of whether or not the recording signal has been recorded on the disk normally takes a user a lot of time.
It is an object of the present invention to solve the aforementioned problems.